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Switching Power Supply Topologies and Design Fundamentals
Published in Nihal Kularatna, DC Power Supplies Power Management and Surge Protection for Power Electronic Systems, 2018
Flyback converters are derived from the buck-boost topology. Low cost and simplicity are the major advantages of the flyback topology. In multiple-output applications, the addition of a secondary winding, a diode, and an output capacitor is all that is required for an additional output. Flyback converter operation can lead to confusion if the designer approaches the design of its magnetics as if it were a transformer. Except for the case of multiple-output windings, the magnetics in a flyback converter are not a transformer. An easy way to view this is as an energy bucket that is alternately filled (when the switch is on) and dumped (when the switch is off). In other words, a flyback magnetic (sometimes called a transformer choke) is an energy-in, energy-out power transfer device where input and output windings do not conduct current simultaneously. A gapped core is used in general to have adequate leakage inductance at the input side for energy storage during the switch-on period.
Isolated DC-DC Converters
Published in Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee, and Digital Control, 2017
Ali Emadi, Alireza Khaligh, Zhong Nie, Young Joo Lee
The fact that all of the output power of the flyback has to be stored in the core as 1/2LI^2 energy means that the core size and cost will be much greater than in the other topologies, where only the core excitation (magnetization) energy, which is normally small, is stored. This means that the transformer bulk is one of the major drawbacks of the flyback converter. In order to obtain sufficiently high stored energy, the flyback primary inductance has to be significantly lower than required for a true transformer, since high peak currents are needed. This is normally achieved by gapping the core. The gap reduces the inductance, and most of the high peak energy is then stored in the gap, thus avoiding transformer saturation (Figures 2.3 and 2.4).
Practical Aspects in Building Three-Phase Power Converters
Published in Dorin O. Neacsu, Switching Power Converters, 2017
Despite being the most critical design component, the actual design and construction of a flyback transformer is beyond the scope of this book as flyback transformer can be acquired off-the-shelves or by order with system-level requirements.
Improvement of energy harvesting capability in grid-connected photovoltaic micro-inverters
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Özgür Çelik, Adnan Tan, Mustafa Inci, Ahmet Teke
In order to achieve a proper design of the flyback converter, the structuring of the high-frequency transformer is very important. In flyback converter topology, the transformer has to store the energy when the switch is on and transfer the stored energy to the load when the switch is off. In order to obtain an optimum high-frequency flyback transformer, the lowest leakage inductance and distribution of air gap length should be carefully adjusted. Firstly, the required magnetizing inductance of the flyback converter with desired criteria can be calculated by using Equation (13). Also, 10% inductor tolerance and 5% safety margin should be considered to determine the exact value. The transformer design can be expressed as an iterative process. Turn ratio and duty cycle determine each other as can be seen from Equation (8). Depending on the selected value of the maximum duty cycle, turn ratio and magnetizing inductance of the transformer can be carried out. After determining the magnetizing inductance and turn ratio, we can specify the parameters of the switching device by using the equations given below (McLyman 2011).
Investigation on modular flyback converters using PI and fuzzy logic controllers
Published in International Journal of Ambient Energy, 2019
V. Jaikrishna, Subranhsu Sekhar Dash, Linss T. Alex, R. Sridhar
Flyback converters are used for low-power, high-voltage applications because of their simplicity, isolation and short circuit protection. The flyback converter facilitates both the step-up and step-down of the input voltage, while maintaining the same ground reference and polarity for input and output. The four possible configurations of a modular converter are input-series output-series (ISOS), input-parallel output-parallel (IPOP), input-series output-parallel (ISOP) and input-parallel output-series (IPOS). These constructions of modular converters have the benefit of external controllers to equalise the current-sharing control for each module. The main advantages of modularisation include each module handling only a part of the total power, high reliability, low cost, easy design and ease of expansion of power system capability (Chen et al. 2009). Each architecture has its own application: that is, IPOS and ISOS configurations are used where high output voltage is required, whereas ISOP and IPOP configurations are used where low output voltage is required, such as in industrial drives, train power systems and undersea observatories (Kim, You, and Cho 2001; Ayyanar, Giri, and Mohan 2004; Kimball, Mossoba, and Krein 2008).
Smart fuzzy-based energy-saving photovoltaic burp charging system
Published in International Journal of Ambient Energy, 2018
N. Govidan, M. Rajasekaran Indra
The proposed model uses the pulse-charging technique to store the energy from the PV panel to the batteries. The concurrent charging of three batteries through DC–DC converters helps in achieving optimum utilisation of the renewable energy, energy saving by maintaining continuity in charging. The utilisation of the negative burp or discharge current to charge a battery or supply a load helps in energy recovery. Using the high-frequency flyback converter is advantageous as it reduces the transformer size. However, avoiding a second interleaved flyback converter and implementing a boost converter helps in reducing cost and complexity of system. Faster charging rate and lesser heating of LAB have been shown. The system enables supplying of multiple loads. It can be taken as an example of a PV power DC distribution system where renewable energy is used to charge and supply different type of loads. The proposed system is applicable for low power applications.